Answer:
1)Na2O
let the valency of Na is x
2(x)+(2)=0
2x+2=0
2x=-2
x=-1
2)ZnO
let the valency of Zn is x
x+2=0
x=-2
3)Al2O3
let the valency of Al is x
2(x)+3(2)=0
2x+6=0
2x=-6
x=-3
4)MgO
let the valency of Mg is x
x+2=0
x=-2
Answer:
= 20.82 g of BaCl2
Explanation:
Given,
Volume = 200 mL
Molarity = 0.500 M
Therefore;
Moles = molarity × volume
= 0.2 L × 0.5 M
= 0.1 mole
But; molar mass of BaCl2 is 208.236 g/mole
Therefore; 0.1 mole of BaCl2 will be equivalent to;
= 208.236 g/mol x 0.1 mol
= 20.82 g
Therefore, the mass of BaCl2 in grams required is 20.82 g
The balanced equation that shows the reaction between oxalic acid and permanganate ion in an acidic medium is: 2MnO4- + 5H2C2O4 + 6H+ -> 2Mn(2+) + 10CO2 + 8H2O. Thus, 1 mole of oxalic acid reacts with 0.4 mole of permanganate ion. This was obtained using stoichiometry:
1 mol H2C2O4 x (2 mol MnO4-/ 5 mol H2C2O4) = 0.4 mol MnO4-
In this redox reaction, the permanganate is reduced to manganese(II) ion.
The molarity of this should be around 0.846
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Formula: M= mols/liters
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So… M= 11.6/13.7⇒ 0.846
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The use of cold methanol is important because it is used to recrystallize or solidify the product.
Since, ice bath is also used in nitration of methyl benzoate because in this reaction the concentrated acid like sulfuric acid is used with water and it is very exothermic.
The formation pure solid from the impure solid compound by mixing with hot solvent and form saturated solution. Now, this solution as cools and pure crystal grows when solubility of the compound decreases. This whole process is called re-crystallization.
learn about re-crystallization
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